Neurotoxins In Shark Fins: A Human Health Concern

Univ. of Miami study shows alarming accumulation of BMAA neurotoxins in shark fins, which may pose a serious threat to shark fin consumers

Shark fins drying in the sun in Kaohsiung before processing. 30 percent of the world’s shark species are Threatened or Near Threatened with extinction. Photo Credit: Shawn Heinrichs for the Pew Environment Group

MIAMI — (February 23, 2012) — Sharks are among the most
threatened of marine species worldwide due to unsustainable
overfishing. Sharks are primarily killed for their fins alone,
to fuel the growing demand for shark fin soup, which is an Asia
delicacy. A new study by University of Miami (UM) scientists in
the journal Marine Drugs
has discovered high concentrations of BMAA in shark fins, a
neurotoxin linked to neurodegenerative diseases in humans
including Alzheimer’s and Lou Gehrig Disease (ALS). The
study suggests that consumption of shark fin soup and cartilage
pills may pose a significant health risk for degenerative brain
diseases.

“Shark fins are primarily derived through finning, a
practice where by shark fins are removed at sea and the rest of
the mutilated animal is thrown back in the water to die,”
said co-author Dr. Neil Hammerschlag, research assistant
professor of Marine Affairs & Policy and director of the RJ
Dunlap Marine Conservation Program (RJD) at UM. “Estimates
suggest that fins from as many as 70 million sharks end up in
soup. As a result, many shark species are on the road to
extinction. Because sharks play important roles in maintaining
balance in the oceans, not only is shark fin soup injurious to
the marine environment, but our study suggests that it is
likely harmful to the people who are consuming them.”

Seven species of shark were tested for this study: blacknose,
blacktip, bonnethead, bull, great hammerhead, lemon, and nurse
sharks. Samples were collected from live animals in waters
throughout South Florida.

“The concentrations of BMAA in the samples are a cause for
concern, not only in shark fin soup, but also in dietary
supplements and other forms ingested by humans, “ says
study co-author Prof. Deborah Mash, Director of the University
of Miami Brain Endowment Bank. The Bank supports basic
and clinical research and holds one of the world’s largest
collection of postmortem human brains encompassing a wide range
of neurological disorders. In 2009, Prof. Mash and her
co-authors published a study in the journal Acta
Neurological Scandinavica, demonstrating that patients
dying with diagnoses of Alzheimer’s Disease and ALS had
unusually high levels of BMAA in their brains up to 256 ng/mg,
whereas normal healthy aged people had no BMAA, or only trace
quantities of the toxin present. “BMAA was first
linked to neurodegenerative diseases in Guam, which resulted in
the progressive loss of structure and function of
neurons.”

The shark study found a similar range and even higher BMAA in
the fins tested. The new study found levels of between
144 and 1836 ng/mg of BMAA, which overlapped the levels we
measured in the brains of Alzheimer’s and ALS victims.
Surprisingly, this level fits with the BMAA levels in fruit
bats examined by Paul Cox, animals which concentrate BMAA from
their diet of cycad seeds. He linked ingestion of fruit bats to
the severe ALS/Parkinsonism dementia that afflicted many people
in Guam.

“Not only does this work provide important information on
one probable route of human exposure to BMAA, it may lead to a
lowering of the demand for shark fin soup and consumption of
shark products, which will aid ocean conservation
efforts,” added Hammerschlag.

The project was funded through a generous donation from the
Herbert W. Hoover Foundation. Established in 1990, the
foundation takes a leadership role in supporting unique
opportunities that provide solutions to issues related to the
community, education, and the environment. Herbert W.
Hoover was an early leader in the conservation movement,
fighting to protect Biscayne Bay and leading the effort to
create Biscayne National Park.

The University of Miami is the largest private research
institution in the southeastern United States. The
University’s mission is to provide quality education,
attract and retain outstanding students, support the faculty
and their research, and build an endowment for University
initiatives. The Department of Neurology,through
interdisciplinary collaborations with other medical
specialists, and scientists in other disciplines, provides both
compassionate quality care for complex neurological disorders
and seeks better treatment and prevention mechanisms through
cutting-edge research.Founded in 2009, the R.J.
Dunlap Marine Conservation Program is a joint program of the
Rosenstiel School of Marine & Atmospheric Science and the
Leonard and Jayne Abess Center for Ecosystem Science and
Policy. The Rosenstiel School offers one of largest, most
comprehensive marine and atmospheric programs in the nation.
The Abess Center encourages innovative interdisciplinary
initiatives that bridge the gap between hard science and
environmental policy. You can support us by visiting ShopforSharks.com. For more
information, please visit www.rjd.miami.edu